The entire disclosure of Japanese Patent Application No. Hei 10-261426 filed on Sep. 16, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an airbag apparatus for protecting an occupant from an impact at the time of a crash of a vehicle and, more particularly, to a side airbag apparatus for protecting an occupant from an impact exerted sideways relative to a vehicle body.
2. Description of the Related Art
Airbag apparatuses that deploy an airbag to protect an occupant at the time of a vehicle crash are in widespread use.
However, such an airbag apparatus may fail to sufficiently protect an occupant depending on the posture or state of the occupant. For example, a front impact airbag apparatus that deploys an airbag into a space between an occupant and an instrument panel to protect the occupant may fail sufficient protect if there is insufficient space to deploy the airbag or if there is insufficient time to deploy the airbag because the occupant is at a position too near the instrument panel, e.g., when the occupant is sitting on a front edge portion of the seat.
Recently, many motor vehicles have been equipped with airbag apparatuses for seats other than the driver""s seat, for example, a passenger-side front seat. Since it is difficult to restore a once-deployed airbag to a state that the airbag can be used again, it is desirable that an airbag apparatus for a passenger-side front seat or the like be controlled so that the airbag will be deployed only when there is an occupant in the passenger-side front seat or the like.
It is advantageous to be able to control the operation of the airbag apparatus in accordance with the presence or absence of an occupant, the sitting posture of an occupant, and the like. Various apparatuses as described below have recently been proposed and put into practical use.
For example, Japanese Patent Application Laid-open No. HEI 7-285364 describes an apparatus that detects whether an occupant is sitting at a non-appropriate position prescribed for the airbag, for example, at a front edge portion of the seat, by using pressure sensors disposed in a front portion and a rear portion of the seat cushion. Upon detecting that an occupant is out of the prescribed sit position, the apparatus warns the occupant. The apparatus is also able to prevent the starting operation of the airbag if the occupant is out of the prescribed position.
Japanese Patent Application Laid-open No. HEI 7-270541 describes an apparatus capable of detecting the presence or absence of an occupant of a seat by using a sensor that detects a permittivity change of a dielectric member disposed in a seat cushion, although the apparatus is not specifically designed for an airbag.
Japanese Patent Application Laid-open No. HEI 8-268220 describes an apparatus that detects whether an occupant of a seat is present or whether an occupant is in such a posture that the occupant is close to the instrument panel, by using an ultrasonic sensor disposed in a compartment ceiling or the like. The apparatus changes the mode of operation of the airbag in accordance with the result of detection.
The aforementioned apparatuses make it possible to appropriately control the operation of the airbag in accordance with the presence or absence of an occupant or the sitting posture of an occupant at the time of an impact to a front portion of the vehicle, that is, a frontal collision.
Besides the above-described airbag apparatuses, side airbag apparatuses for protecting an occupant at the time of an impact to a side of a vehicle body, that is, a side collision, have been proposed and used. A typical side airbag apparatus deploys a side-impact airbag (side airbag) into a space between an occupant and a side portion of the vehicle body at the time of a side collision so as to protect the occupant, more specifically, side portions of the occupant""s body, from an impact caused by the side collision or a compression caused by deformation of the vehicle body. Such a side airbag apparatus is normally disposed in a side portion of a seatback, a vehicle door, or the like.
The side airbag apparatuses may also fail to achieve a sufficient protecting effect depending on the sitting posture of an occupant. For example, if a side airbag is deployed when a relatively small person, for example, a child, is leaning against a side body portion of the vehicle, the protecting effect is remarkably reduced as described below.
FIGS. 11 through 14 illustrate relationships between the sitting posture of an occupant and a side airbag deployed at the time of a side collision.
FIG. 11 shows an average-built occupant P1 sitting in a proper posture. FIG. 12 illustrates an average-built occupant P1 leaning against a side vehicle body portion (door D). FIG. 13 illustrates a small-built occupant P2, for example, a child or the like, sitting in a proper posture. FIG. 14 illustrates a small-built occupant P2 leaning against a side vehicle body portion (door D).
If the average-built occupant P1 is sitting in a seat S in the proper sitting posture as shown in FIG. 11, the side airbag is deployed into a space A between a side portion of the trunk of the average-built occupant P1 and the door D. The side airbag is also deployed into the space A between the door D and a side portion of the trunk of the small-built occupant P2, for example, a child, if the small-built occupant P2 is sitting in the proper sitting posture as shown in FIG. 13. In these cases, a sufficiently high effect of the side airbag protecting the occupant P1, P2 from the impact at the time of a side collision or compression caused by deformation of vehicle body or the like is achieved.
If the average-built occupant P1 of the seat A is leaning against the door D, an arm or the trunk of the occupant P1 is located in the space A for deployment of the side airbag. Therefore, proper deployment of the side airbag is impeded, so that the occupant protecting effect may not be sufficiently achieved. However, even if the trunk or an arm of the average-built occupant P1 is located in the space A, the side airbag can be deployed so as to substantially achieve its protecting effect provided that there is a certain space between an upper trunk portion of the average-built occupant P1 and the door D.
If the small-built occupant P2, for example, a child or the like, sitting in the seat A is leaning against the door D as shown in FIG. 14, the head of the occupant P2 is located in the space A for deployment of the side airbag. In this case, too, there is a danger that the proper deployment of the side airbag will be impeded. Even if the side airbag is deployed, the side airbag, which is designed to be deployed to protect an occupant""s trunk portion, is deployed between the head of the small-built occupant P2 and the door D. Therefore, if the small-built occupant P2 in the seat A is leaning against the door D, the occupant protecting effect of the side airbag is remarkably reduced.
The above-described apparatuses, which detect the sitting posture of an occupant at the time of a frontal collision and controls the frontal impact airbag in accordance with the result of detection, are not designed taking the operation of a side airbag into consideration. Moreover, the aforementioned apparatuses are not able to detect whether an occupant of a seat is leaning against a side vehicle body portion. Therefore, the apparatuses are not able to properly control the operation of a side airbag in accordance with the occupant sitting posture or situations as described above.
Accordingly, the present invention provides a side airbag apparatus having controllable modes of operation, the modes of operation being controlled in accordance with the presence or absence of an occupant of a seat or the sitting posture of an occupant.
In accordance with one aspect of the invention, a side airbag apparatus is provided with an occupant sensor that detects whether an occupant is present at a vehicle seat, excluding a case where an occupant having a constitution smaller than a predetermined constitution is leaning against the side vehicle body portion, and a control means for controlling operation mode of the side airbag in accordance with whether an occupant is present on the basis of detection by the occupant sensor.
Therefore, it becomes possible to discriminate a case where an occupant is not present or a small-built occupant, for example, a child or the like, is sitting in the seat and leaning against the side vehicle body portion, from other cases. Hence, in accordance with the sitting posture of an occupant or the state of occupancy of the seat, the side airbag apparatus is able to operate the side airbag in a suitable mode, for example, a mode in which the side airbag is deployed at a low pressure or a low speed, or a mode in which the side airbag is deployed stepwise in a plurality of divided stages, or the like, or to prevent unnecessary operation of the side airbag.
The control means may, based on the occupant sensor, permit operation of the side airbag if an occupant is present, and prohibit operation of the side airbag if the an occupant is not present.
Therefore, the operation of the side airbag is prohibited in a case where an occupant is not present and in a case where a small-built occupant is sitting in the seat and leaning against the side vehicle body portion. In the other cases, the operation of the side airbag is permitted. Hence, it becomes possible to prevent unnecessary operation of the side airbag.
In the side airbag apparatus, the occupant sensor may detect whether an occupant is present with respect to one of the following: a site that is located in the upper portion of a seatback and shifted from [a] the center of the seatback in a widthwise direction thereof toward a vehicle body center and a site that is located in the upper portion of the seatback of the seat and near the center of the seatback.
By detecting whether an occupant is present with respect to one of the above described sites, the occupant sensor makes it possible to discriminate a case where an occupant is not present and a case where a small-built occupant is sitting in the seat and leaning against the side vehicle body portion, from other cases. Therefore, it becomes possible to facilitate suitable operation of the side airbag in accordance with the sitting posture of an occupant and prevention of unnecessary operation of the side airbag.
In some conventional vehicles, an occupant sensor is provided in a seat cushion or the like for detecting the presence or absence of an occupant in order to control various frontal impact safety devices, for example, a frontal impact airbag, a seat belt pretensioner, a head protecting airbag (curtain shield airbag) or the like. In the above-described construction, the occupant sensor for the side airbag apparatus can also be used to control these safety devices. Through the common use of a sensor for controlling various safety devices, the entire vehicle construction can be simplified and the production cost can be reduced.
In the side airbag apparatus, the occupant sensor may have a detection range for detecting the presence of an occupant, the detection range being defined as a region that includes a vehicle body center-side body contour of an occupant having a predetermined constitution and leaning against the side vehicle body portion and that extends toward the vehicle body center.
By setting the detection range of the occupant sensor in this manner, it becomes possible to detect the presence or absence of an occupant of the seat of the vehicle, excluding the case where an occupant has a constitution smaller than the predetermined constitution and is leaning against the side vehicle body portion. Therefore, the side airbag apparatus is able to precisely discriminate the case where an occupant is not present or a small-built occupant is leaning against the side vehicle body portion from other cases, while requiring only a simple apparatus construction. Hence, it becomes possible to easily and reliably operate the side airbag in accordance with the state of sit of an occupant and prevent unnecessary operation of the side airbag.
In the side airbag apparatus, the detection range of the occupant sensor may have a shape that is defined as a generally inverted trapezoidal shape or a generally inverted triangular shape having, as an oblique line, a sloped line segment extending along the vehicle body center-side body contour of the occupant having the predetermined constitution and leaning against the side vehicle body portion.
Therefore, the side airbag apparatus becomes able to precisely discriminate the case where an occupant is not present and the case where a small-built occupant is leaning against the side vehicle body portion from other cases, while requiring only a simple apparatus construction. Hence, it becomes possible to easily and reliably operate the side airbag in accordance with the sitting posture of an occupant and prevent unnecessary operation of the side airbag.
In the side airbag apparatus, the control means may change the operation mode of the side airbag only if a state detected by the occupant sensor continues for at least a predetermined length of time. Therefore, the side airbag apparatus becomes able to prevent a false detection of an occupant.
In the side airbag apparatus, the occupant sensor may be one of a capacitance sensing type sensor and an impedance change sensing type sensor. By employing a proximity sensor of a capacitance sensing type sensor or an impedance change sensing type sensor whose detection range can easily be defined as a desired shape, the construction of the occupant sensor can be simplified.
The side airbag apparatus may further include an occupancy sensor that detects whether an occupant is sitting in the seat, the occupancy sensor being formed by a sensor other than the capacitance sensing type sensor and the impedance change sensing type sensor, and an initialization means for initializing the occupant sensor on the basis of a result of detection performed by the occupancy sensor.
The output of a capacitance sensing type or impedance change sensing type sensor changes depending on humidity, so that the detection precision of the sensor is limited. However, the above-described construction in which the occupancy sensor is provided for detecting whether an occupant is sitting in the seat, separately from the occupant sensor, and the initialization means initializes the occupant sensor on the basis of a result of detection performed by the occupancy sensor, avoids the effect of humidity on the occupancy sensor, and therefore allows a further improvement in the detection precision of the sensors. Therefore, the sitting posture of an occupant can be more reliably detected, and the operation of the side airbag can be more precisely controlled.
In the side airbag apparatus, the occupancy sensor may be a pressure sensing type sensor provided in a seat cushion of the seat.
This simple construction including the pressure sensing type sensor in the seat cushion makes it possible to detect the presence or absence of an occupant and to initialize the occupant sensor on the basis of the result of detection performed by the occupancy sensor. Therefore, the detection precision of the occupant sensor can be further improved.
In the side airbag apparatus, the initialization means may update a criterion of a value of output of the occupant sensor for determining whether an occupant is present, in accordance with a value outputted by the occupant sensor when absence of an occupant is detected by the occupancy sensor.
When the absence of an occupant is detected by the occupancy sensor, a portion of the body of an occupant is normally not present in the detection range of the occupant sensor. Therefore, by initializing the criterion for determining whether an occupant is present through the use of the occupant sensor in accordance with the value outputted by the occupant sensor, the side airbag apparatus becomes able to reliably detect the sitting posture of an occupant regardless of a change in the sensor output depending on humidity.
The initialization means may initialize the occupant sensor if a state detected by the occupancy sensor continues for at least a predetermined length of time. Therefore, the side airbag apparatus becomes able to reliably determine whether an occupant of the seat is present and prevent false initialization of the occupant sensor.
In accordance with another aspect of the invention, a side airbag apparatus for protecting an occupant by deploying a side airbag between a side portion of the occupant and a side vehicle body portion at the time of an impact, includes a sensor capable of detecting a state that an occupant having a constitution smaller than a predetermined constitution is leaning against a side vehicle body portion, wherein an operation mode of the side airbag is changed in accordance with a result of detection performed by the sensor.
Therefore, it becomes possible to detect a state that an occupant having a constitution smaller than the predetermined constitution is leaning against the side vehicle body portion. Hence, the side airbag apparatus is able to operate the side airbag in a suitable mode, for example, a mode in which the side airbag is deployed at a low pressure or a low speed, or a mode in which the side airbag is deployed stepwise in a plurality of divided stages, or the like, or to prevent unnecessary operation of the side airbag.